Method of forming a construction member of glass fiber elements

ABSTRACT

HARDENABLE RESIN. THE RESIN OF THE FABRIC IMPREGNATES THE INTERSTICES BETWEEN THE RODS FORMING A HIGH STRENGTH INTEGRAL, HOMOGENEOUS, BONDED MEMBER. THE METHOD OF THE INVENTION IS PRACTICED IN BOTH THE FORMING OF POLE AND PLANK TYPE MEMBERS, AND THE BASIC INVENTIVE CONCEPTS MAY BE PRACTICED IN THE FORMING OF HOLLOW AND SOLID MEMBERS.   THE INVENTION PERTAINS TO A METHOD FOR FORMING A CONSTRUCTION MEMBER OF GLASS FIBER ELEMENTS IMPREGNATED WITHA HARDENED RESIN. THE METHOD INCLUDES THE INTERPOSING OF ELONGATED, HIGH DENSITY, GLASS FIBER RODS CONSISTING OF A PLURALITY OF LONGITUDINALLY DISPOSED GLASS FIBERS BONDED TOGETHER WITH A HARDENED BINDER RESIN WHILE UNDER TENSION BETWEEN LAYERS OF GLASS FIBER FABRIC IMPREGNATED WITH A

Jin. 9, 1913 A. MEDLER 3,709,154

METHOD OF FORMING A CONTRUCTION MEMBER OF GLASS FIBER ELEMENTS OriginalFiled Jan. 24, 1968 2 Sheets-Sheet 1 T7611 T1612 T1613 T16. 14

INVENTOR ALBERT MEDLER ATTORNEYS am no or FORMING AQON'IfiUCTION MEMBEROF cuss FIBER ELEMENTS Original Filed Jan. 24, 1968 2 Sheets-Sheet 2 I NVENTOR //Z ma -w //0 ii 94 m4 Y ATTORNEYS United States Patent Ofice3,709,754 Patented Jan. 9, 1973 3,709,754 METHOD OF FORMING ACONSTRUCTION MEMBER OF GLASS FIBER ELEMENTS Albert Medler, Jackson,Mich., assignor to Plastigage Corporation, Jackson, Mich.

Original application Jan. 24, 1968, Ser. No. 700,287, now Patent No.3,574,104, dated Apr. 6, 1971. Divided and this application Sept. 21,1970, Ser. No. 74,151

Int. Cl. B31c 9/00; B65h 81/00; F161 9/16 US. Cl. 156-461 2 ClaimsABSTRACT OF THE DISCLOSURE The invention pertains to a method forforming a construction member of glass fiber elements impregnated with ahardened resin. The method includes the interposing of elongated, highdensity, glass fiber rods consisting of a plurality of longitudinallydisposed glass fibers bonded together with a hardened binder resin whileunder tension between layers of glass fiber fabric impregnated with ahardenable resin. The resin of the fabric impregnates the intersticesbetween the rods forming a high strength integral, homogeneous, bondedmember. The method of the invention is practiced in both the forming ofpole and plank type members, and the basic inventive concepts may bepracticed in the forming of hollow and solid members.

This application is a division of application Ser. No. 700,287, filedIan. 24, 1968, now Pat. No. 3,574,104, granted Apr. 6, 1971.

BACKGROUND OF THE INVENTION The invention pertains to the field of artof making construction members which are fabricated of separatecomponents of similar and chemically compatible elements, namely, glassfiber and a hardened resin, to produce improved mechanicalcharacteristics, particularly with respect to resisting bending andlateral deflection.

A number of attempts have been made to produce acceptable poles, planksand other construction members of glass fibers impregnated with ahardened resin. US. Pat. 3,013,584 illustrates a tubular supportingmember which was produced in order to employ the advantages of glassfiber materials. While the aforementioned patent illustrates the conceptof inner and outer tubular glass fiber portions having a honeycombinterposed therebetween, the construction of prior art devices is not ofsuch a nature as to provide the necessary resistance to bending momentsand lateral deflection which is often required in a construction member.For instance, it is highly desirable to use a construction material inthe manufacture of electric power transmission systems which isnonconducting, resistant to weathering and corrosive influences,relatively inexpensive, and attractive in appearance. While most lowervoltage transmission poles were previously formed of wood, othermaterials are now being employed in order to overcome the lack ofuniformity of wood transmission poles with respect to appearance andresistance to the weather. Furthermore, in that it is the tendency forwood power transmission components to bend under high lateral forces, itis necessary to use multiple components and guy cables with woodtransmission components in order to produce the necessary resistance tobending. For instance, electrical utility system cross arm dead-endsconventionally formed of wood are unsightly due to the necessity forusing two cross arm members of relatively large cross section to providesufficient strength characteristics to resist the bending forces imposedthereupon by the electric transmission lines.

Pole type construction members formed of glass fiber components have notheretofore had sufiicient resistance to bending and flexing to permitelongated poles such as would be suitable in the electric transmissionsystem art to be produced. Previous glass fiber construction memberarrangements were unable to overcome the inherent tendency of relativelylong and slender glass fiber members to bend or whip.

SUMMARY OF THE INVENTION The invention provides an arrangement wherebyglass fiber components may be assembled in such a manner as to produceelongated construction members, such as poles, columns, posts, tubes orplanks which have superior strength characteristics, and are especiallyresistant to lateral bonding and flexing.

In the basic practice of the invention a plurality of elongated highdensity rods or strips formed of glass fibers impregnated with ahardened resin are interposed or sandwiched between a plurality ofsuperimposed layers of glass fiber fabrics impregnated with a hardenedresin. The construction member is preferably assembled by placing thefabric upon both sides of the glass fiber rods after the rods are fullycured and completely set. The resin impregnated fabric is applied to therods, which are generally disposed in a side by side relationship, andthe resin will directly contact the rods and work into the intersticestherebetween during the formation of the construction member. Upon theresin within the fabric hardening, the superimposed fabric layers willbe bonded to each other, and the fabric layers will likewise be firmlybonded to the glass fiber rods.

High density glass fiber rods have excellent resistance to tension andcompression forces, and the combination of the rods firmly bonded to theglass fiber fabric layers produces a construction which has superiorresistance to lateral or bending forces. In particular, when theinvention is utilized to form a cylinder or tube wherein the glass fiberrods are related circumferentially about an elongated axis, and theglass fiber fabric is radially interposed inwardly and outwardly withrespect to the rods, excellent characteristics which resist bending areobtained.

The concepts of the invention may be used to form a member having across-sectional configuration which results from the shape of a coremember upon which the superimposed fabric is wound in a spiral manner,or the resultant configuration of the construction member may bedetermined by a mold which is normally employed gheein a plank ornontubular construction is to be de- Usually, the fabric which is to beused will be a woven fabric, and preferably, the glass fibers of thewoven fabric which extend in the longitudinal direction of the resultantconstruction member are continuous. Likewise, the fibers within the rodsare preferably of a continuous form extending the length of the rods,and the length of the construction member. However, it is understoodthat the fabric which may be used could also be of the mat type whereinthe glass fibers are indiscriminately arranged, or the fabric may be ofa combination of woven and mat construction or of a roving construction.

BRIEF DESCRIPTION OF THE DRAWING The concepts of the invention will beappreciated from the following specification and attached drawingswherein:

{FIG 1 is a perspective view of an electrical transmission pole andcross arm dead-end assembly wherein both the pole and dead-end areconstructed in accord with the invention,

FIG. 2 is a cross-sectional view illustrating the arrangement of thecomponents of the cross arm dead-end as taken along section IIII of FIG.1,

FIG. 3 is a perspective, peeled, sectional view of a tubularconstruction member formed in accord with the invention illustrating therelationship of the various components,

FIGS. 4 through 7 are elevational sectional views of various types ofcore constructions and configurations which may be used with tubularconstructional members formed in accord with the invention,

FIG. 8 is a perspective view of an embodiment of a tapered pole memberutilizing the concept of the invention, portions adjacent the upper andlower ends thereof being bnoken away to illustrate the relationship ofthe glass fiber rods,

FIG. 9 is a perspective view of a plank type construction memberutilizing the inventive concept of the invention,

FIG. 10 is an elevational, sectional view of the plank of FIG. 9 astaken along section XX thereof,

FIGS. 11 through 14 are elevational end views of various configurationsof glass fiber rods which may be used in accord with the invention,

FIG. 15 is an elevational view of a utility pole having a bracket formedin accord with the invention,

FIG. 16 is a view of the bracket, per se, as taken from the right ofFIG. 15,

FIGS. 17 and 18 are elevational sectional views of the bracket takenalong sections XVIIXVII and XV'LEII- XV'III of FIG. 15,

FIG. 19 is a side elevational view of a mold in which the bracket ofFIGS. 15-18 may be formed, and

FIG. 20 is an elevational sectional view taken along section XX-XX ofFIG. 19.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a verticallydisposed construction member 10 in accord with the invention forms apole which would be set into a hole, and the pole may be of considerablelength, for instance, between thirty and forty feet. Near the upper endof the pole 10 a bracket 12 is used to afiix a cross arm dead-end 14thereto. The bracket 12 includes cylindrical segment surface portions 16and 18 which coact with the outer surfaces of the pole and dead-end,respectively, and bolts 20 extending thnough holes drilled in the poleand dead-end affix the deadend, and bracket to the pole. The dead-end14. is constructed in a manner identical to that of the pole 10, but isof a smaller diameter. Near the ends of the deadend horizontallyextending holes are formed for receiving eye bolts 22 having associatednuts and washers whereby transmission lines, not shown, may be directlyattached to the eye bolts, or conventional insulators attached to theeye bolts, to which the transmission lines are then fixed. Considerablebending forces are applied to the dead-end, and public utilityspecifications closely limit the amount of deflection, permissalble witha deadend of this type.

The construction of the pole 10 and the dead-end 14 is such as to resultin a tubular construction member having a cylindrical outer surface. Theinternal arrangement of components of the pole and dead-end will beapparent from FIGS. 2 and 3. A tubular core member is employed, uponwhich the innermost layers of glass fiber fabric are wound. The core 24may consist of a tube of plastic material, paper, or other materialwhich is relatively inert, and nonconductive. The core 24 adds little tothe strength characteristics of the resultant construction member, andis basically employed to form the shape of the member, and provides abase upon which to build up the other components. The core 24 will be ofa length equal to that of the desired construction member. A glass fiberfabric is spirally wound upon the core 24 in such a manner that thesuperimposed layers of the fabric provide an inner portion 26 which isof a cylindrical configuration, having an inner diameter equal to theouter diameter of the core, and a circumference 28 having a diameterwhich is determined by the amount of glass fiber fabric Wound upon thecore.

Glass fiber fabric is available in rolls of considerable length, and ofvarious Widths. For instance, a roll of glass fiber fabric having awidth of forty-eight inches may be used in forming construction membersin accord with the invention. The operator unrolls a length of fabricfrom the supply roll which is equal to the length of the desiredconstruction member, and this length is severed from the supply roll.The fabric is then impregnated with a hardenable resin, such as epoxy, apolyester compound, or a phenolic compound. Thereupon, the resinimpregnated fabric is spirally wound widthwise tightly upon the core 24to form the spirally wound inner portion 26, FIG. 2. -If a greaterradial thickness of the inner portion 26 is desired than is obtainablewith a fabric of forty-eight inches width, a second length may beunrolled from the supply roll, and impregnated with the hardenable resinand thereupon wound over the first length of glass fiber fabric woundupon the core.

After sufiicient glass fiber fabric has been wound on the core 24 toform the inner portion 26 the operator Will then place a plurality ofhigh density glass fiber rods 30 in side by side substantiallycontiguous relationship upon the circumference 28 of the inner portion26 substantially parallel to the axis of the core. The rods 30 in theillustrated embodiment are of a cylindrical configuration and are of alength equal to the length of the construction member desired. The rods30 are disposed completely about the inner portion circumference 28, andmay be readily located in position due to the relatively tacky or stickyconsistency of the resin within the fabric previously applied to thecore 24. The application of the rods 30 to the inner portion will causeresin within the fabric to work into the voids between the rods,eliminating the occurrence of voids in the region occupied by the rodsand resulting in a solid, homogeneous connection between the rods andfabric.

The rods 30 may be formed in a manner as disclosed in U.S. Pat.2,684,318. Such rods are formed of glass fiber filaments impregnatedwith a hardened resin while under tension, and drawn through a sizingdye. The rods may be ground after the resin has set and cured, ifdesired, wherein the rods will be of an accurate uniform diameter or thesizing may remain as that determined by the forming die.

After the rods 30 are disposed and placed upon the circumference 28 ofthe fabric inner portion 26, a fabric outer portion 32 is wound upon therods. The outer portion 32 is wound upon the rods 30 in a manner similarto the winding of the inner portion 26 upon the core 24. A length ofglass fiber fabric is unrolled from the supply roll equal to the lengthof the desired construction member, and impregnated with the hardenableresin. The fabric is then spirally wound widthwise upon the rods 30.Several lengths of fabric may be wound upon each other to form the outerportion 32 until the desired radial thickness is produced which resultsin the required physical characteristics of the particular constructionmember being manufactured. As the glass fiber fabric forming the outerportion 32 is spirally wound upon the rods 30 the resin within thefabric will enter the voids between the rods disposed towards the outerportion fabric, and the resin will produce a solid, homogeneous bondingbetween the outer fabric portion 32 and the rods 30.

Since the core 24 of the embodiment of FIGS. 1-3 is of a cylindricalconfiguration, the resultant configuration of the member will becylindrical, and only the outermost layer of the fabric outer portion 32will be visible. As the impregnated fabric provides a pleasingappearance, further treatment, such as paint, of the construction memberis not necessarily required. If a color is desired, the coloring may bedirectly introduced into the resin to provide a permanent appearance tothe construction member, or the member could be painted.

The impregnation of the fabric of the inner and outer portions 26 and 32with the hardenable resin causes the adjacent fabric layers to behomogeneously bonded together when the resin sets. Additionally, thepresence of the resin in direct engagement with the rods 30 results infirmly bonding the rods in a chemically compatible manner to the innerand outer portions 26 and 32 wherein a completely integral andhomogeneous member is defined.

The fabric used to form the portions 26 and 32 may be of most of thefabric sheet material available for glass fiber construction purposes,such as woven fabric, mat or roving. The preferred fabric is of thewoven type having glass fiber filaments which extend the length of theconstruction member being formed and filaments which are spirally woundabout the member core and are disposed at approximately right angles tothe length of the member. This type of woven fabric thereby disposes itsfilaments in the directions which are most effective to resist lateralbending of the member.

The resultant construction member has extraordinary resistance tofracturing and lateral or bending deflection. Such resistance is greaterthan that which is produced by a plurality of glass fiber rods bondedtogether, and greater than that provided with a constructional memberconsisting solely of spirally wound fabric impregnated with a hardenedresin. It is believed that the improved resistance to bending isproduced by the fact that bending forces imposed upon the member producetension forces in approximately one-half of the rods 30, and compressionforces on the other half of the rods due to the radial spacing of therods from the axis of the member. Relative axial shifting between thefabric portions and rods is not possible, due to the bond created by theresin, and the excellent tension and compression resistancecharacteristics of the dense glass fiber rods, radially located from theaxis of the construction member produces excellent resistance to lateraldeflection.

Thus, an all glass fiber construction member is produced which providesthe dielectric, noncorrosive and appearance advantages of glass fiber,while producing very high resistance to lateral deflection.

FIGS. 4 through 7 illustrate various types of cores which may be used inthe practice of the invention. FIG. 4 illustrates a cylindrical core 34which may be formed of paper or other inexpensive material internallysupported by a cross web 36. In this manner a light weight core can beprotected against collapse during formation of the construction member.FIG. 5 illustrates a rectangularly shaped synthetic plastic core 38which would be used if a construction member having a rectangular outerconfiguration, rather than a cylindrical configuration, is desired.Likewise, FIG. 6 illustrates an elliptical core 40 which may be formedof plastic, paper or other material which would result in an oval orelliptical construction member. FIG. 7 illustrates a core 42 formed ofsolid plastic foam material, such as urethane foam. The illustrated coreis cylindrical in configuration, but, of course, other crosssectionalshapes of foam can be utilized. Hard urethane foam has suificientstrength to permit wrapping of the fabric layer inner portion 26thereupon, and is inexpensive.

It will be appreciated that it is not necessary to use a core at all, inthe practice of the invention. A greased mandrel could be used uponwhich the inner portion 26 is wound, and upon the resin setting, themandrel could be withdrawn from the inner portion. Also, in the eventthat a substantially solid construction member is desired the innerportion 26 could be tightly wound upon itself without a core and wouldbe solid, rather than tubular in configuration.

FIG. 8 illustrates a tapered construction member, such as a pole 44,wherein the diameter of the construction member at the lower end 46 isgreater than at the upper end 48. The tapered configuration can beproduced by using a conical core 50, or the core may be cylindrical butthe inner fabric portion 52 is applied to the core in such a manner thatthe radial thickness of the portion increases toward the pole lower end.Such a variable radial thickness would be accomplished by using a fabricof a length less than that of pole 44 and applying a greater number offabric layers adjacent the lower end than adjacent the upper end. Afterthe inner portion 52 is wound upon the core the outer circumference ofthe inner portion varies throughout its length from the lower end 46 tothe upper end 48.

In the embodiment of FIG. 8 the glass fiber rods 54 are disposed incontiguous relationship to each other adjacent the upper end 48.However, due to the larger diameter and circumference of the fabricinner portion 52 adjacent the lower end 46 the rods 54 will becircumferentially spaced from each other, as is apparent from thedrawing. After the rods 54 are located upon the inner portion 52, theouter portion 56 of resin impregnated fabric is wound upon the rods toform the member in the manner previously described. The embodiment ofFIG. 8 will have the pleasing appearance of a tapered construction,which is particularly suitable in a pole, and if the taperedconfiguration results from a greater thickness of the inner portion 52adjacent the lower end 46 variable strength characteristics throughoutthe length of the pole are achieved.

A plank or other noncircular configuration of construction member may beformed utilizing the concepts of the invention. In FIGS. 9 and 10 theplank 58 has an outer rectangular configuration which is formed bymolding the plank within a mold having a rectangular cavity. In theformation of the plank of FIGS. 9 and 10 several layers 60 of glassfiber fabric are laid in the bottom of the mold 61, shown in dottedlines in FIG. 10, to cover the entire area of the cavity. After theseveral layers 60 of glass fiber are positioned in the mold and theselayers are impregnated with a hardenable resin, glass fiber rods 62 aredisposed in contiguous relationship to each other extending throughoutthe length of the mold. The rods 62 extend parallel to the length of themold, and after being placed upon the lower fabric layers 60, additionalresin impregnated layers 64 of glass fiber fabric are superimposed uponthe rods. As in the previously described embodiment, the fabric resinwill fill the interstices between the rods 62 and the plank having across section as represented in FIG. 10 is produced upon placing the tophalf 66 of the mold upon the cavity portion 61 thereof. The resultantintimate bonding between the glass fiber fabric layer portions 60 and 64and rods 62 produces a construction mmeber 58 of superior strengthcapable of withstanding tension and compression forces, and highlyresistant to lateral deflection.

FIGS. 11 through 14 illustrate various cross-sectional configurations ofhigh density glass fiber rods which may be used in the practice of theinvention, and it is to be understood that the inventive concepts arenot limited to rods of circular configuration. For instance, elliptical,hexagonal, rectangular and keystone shaped rods may be used. Asmentioned above it is preferred that such rods are formed of glass fiberextending the length of the rods whereby superior resistance to tensionand compression forces is obtained.

FIGS. 15 through 20 are directed to another construction memberconstructed in accord with the invention which uses the inventiveconcepts thereof in a bracket of the cantilever type which may beafiixed to utility electrical system poles for the support of insulatorsand conductors, lights, or other accessories. In FIG. 15 the upperportion of a pole 68 is illustrated having a bracket 70 which is afiixedthereto. The pole 68 is preferably constructed in a manner similar tothe pole 10, in accordance with the previously described embodiment.

The bracket 70 is attached to the upper end of the pole 68 for thepurpose of supporting insulators 72 at the free end thereof. A conductorwould normally be supported by the insulator 72.

The bracket 70 includes a free end 74 to which the insulator 72 depends.The lower end of the bracket includes a portion 7 6 which is affixed tothe pole 68, and the curved intermediate portion of the bracket isindicated at 7 8.

The bracket 70 is attached to the pole 68 by means of bolts extendingthrough holes 8 and 82, FIG. 16, defined through the bracket portion 76.If desired, the hole 82 may be of an elongated form to compensate forminor dimensional variations existing in the pole bolt holes. Bolts 84extend through drilled holes in the pole 68, and also extend through thebracket holes 80 and 82 wherein the arcuate plates 86 may be locatedunder the bolt nuts to eliminate localized stress points upon thebracket 70 when the nuts of the bolt 84 are tightened to firmly affixthe bracket 70 to the pole 68.

The bracket 70 may basically be considered to be of a plank form.However, the bracket is curved in a longitudinal direction as isapparent from FIG. 15, and is also provided with arcuate surfacesextending in a transverse direction, as will be later described.

The bracket 70 is formed by a molding operation of glass fiber fabricand glass fiber rods, assembled and bonded together in a manner somewhatsimilar to that described above with respect to the foregoingembodiments. As shown in FIGS. 17 and 1 8, the bracket includes aportion 88 which consists of a plurality of superimposed layers of glassfiber fabric impregnated with a hardenable resin. A plurality of highdensity glass fiber rods 90 are disposed adjacent the glass fiber fabricportion 88 in such a manner that the rods are substantially contiguousto each other in a side-by-side relationship, and extend the length ofthe bracket.

An intermediate glass fiber fabric portion 92 consist ing of a pluralityof glass fiber fabric layers impregnated with a hardened resin aredisposed upon the opposite side of the rods 90, with respect to theglass fiber fabric portion 88, and the resin within the portions 88 and94 will fill the interstices intermediate the rods 90.

Another layer or series of high density glass fiber rods 94 is includedwithin the bracket 70 disposed adjacent the intermediate fiber portion92., and these rods are related to each other in a manner similar to thepreviously described rods 90. The third glass fiber fabric portion 96 isdisposed adjacent the rods 94 upon the opposite side thereof withrespect to the portion 92, and the portion 96 is similar in compositionand assembly to the portion 88.

The resultant cross-sectional configuration of the bracket 70 will beappreciated from FIGS. 17 and 18, wherein the bracket will be formedsolely of glass fiber components of both fabric and rod character.

The free end of the bracket 70 is preferably of a flat rectangular crosssection as is apparent in FIG. 17. However, except for that bracketportion 74 immediately adjacent the free end of the bracket, theremaining length of the bracket 70 is preferably of a convex-concaveconfiguration as is apparent from FIG. 18. Thus, the convexconcave crosssectional configuration of the bracket 70 will include a convex surface98 and a concave surface 100. The edges 102 are preferably substantiallyparallel and are related to the surfaces 98' and 100 in a manner thatwill be apparent from FIG. 18.

The radius of the bracket surface 100 preferably substantiallycorresponds to the radius of the pole 68. Thus, upon mounting thebracket 70 upon the pole 68 in the manner illustrated, a solidconnection of the bracket to the pole is assured which prevents theexistence of localized stresses on the bracket portion 76, and alsoaligns the bracket portion 76 with the longitudinal axis of the pole 68.

The bracket 70 may be formed in a mold shown in simplified form in FIGS.19 and 20. In its simplest form the mold may be of metal, wood or glassfiber consisting of a lower portion 104, and an upper portion 106. Theparting line between the mold portions is represented at 108. A recess110 is defined within the mold portion 104 having a convex surface inorder to form the concave surface 100. The recess 110 is defined by theedge surfaces 112. The uppermost portion 106 includes a concave surface114 which determines the configuration of the convex surface 98 of thebracket.

The bracket 70 is formed by laying a plurality of glass fiber fabricstrips within the mold recess '110, wherein the strips are of a lengthequal to the cavity, and of a width substantially equal to that definedby the edge surfaces 112. A sufficient number of glass fiber fabriclayers are positioned within mold recess 110' to define the thickness ofthe bracket portion 96 desired. Thereupon, a plurality of high densityglass fiber rods 94 are laid in contiguous side-by-side relationshipupon the fabric forming the portion 96'. After the rods 94 are locatedin place, the intermediate glass fiber portion 92 is built up upon therods 94 by a plurality of glass fiber fabric layers impregnated with ahardenable resin. When the proper thickness of portion 92 has beenachieved the rods 90 are therein laid upon the portion 92 inside-by-side relationship, and the glass fiber fabric portion 8 8: isthen built up upon the rods 90 with a plurality of fabric layers. Theuppermost portion 106 is then laid in place which will shape the surface98 in accord with the mold recess 114. After the bracket 70 has hardenedit may be removed from the mold, and the ends may be trimmed, ifdesired. The holes and 82 are preferably drilled into the bracket.

As in the previously described embodiments of the invention, thefabrication of bracket 70 will completely fill the interstices betweenthe rods and 96 with hardenable resin with which the glass fiber isimpregnated. Thus, a solid, homogeneous bracket will be formed. It is tobe noted that in the drawings of all of the embodiments the resinfilling the interstices between the rods is not illustrated by shadingin order to prevent obscuring the relationship between the rods and theadjacent glass fiber portions. The bending stress that is placed uponthe bracket 70 due to the weight of the conductor connected to theinsulator 72 will place the rods 94 in tension, while the rods 90 willtend to be in compression. By separating the rods 90 and 94 by theintermediate glass fiber fabric portion 92 the rods are thus able to addconsiderable strength to the backet 70 over the strength which would bepresent if the bracket was entirely formed of glass fiber fabric withoutrods. As the rods 90 and 94 are spaced from the neutral axis of thebracket, with respect to lateral bending stresses, the construction ofthe bracket 70 is more effective to resist bending then is theconstruction utilized in the manufacture of plank 58. Also, theconvex-concave configuration of the bracket 70 itself contributes tostrengthening the bracket against lateral deflection.

While several of the illustrated embodiments formed in accord with theinvention are utilized in the electrical power transmission system artit will be appreciated that the inventive concepts find wide use in awide variety of the construction and building arts. The invention isdescribed in conjunction with electrical power transmission devices inthat the high strength, resistance to corrosion, dielectriccharacteristics and attractive appearance of components constructed inaccord with the invention are highly desirable in this particular art.

It is appreciated that various modifications to the inventive conceptsmay be apparent to those skilled in the art without departing from thespirit and scope thereof, and it is intended that the invention bedefined only by the following claims.

I claim:

1. The method of forming an elongated construction member of glass fibermaterial comprising the steps of spirally wrapping a glass fiber fabricimpregnated with a hardenable binder resin about an elongated core toform several superimposed layers, placing a plurality of elongated, highdensity, glass fiber rods consisting of a plurality of longitudinallydisposed glass fibers bonded together with a hardened binder resin Whileunder tension upon and about the circumference of the wrapped fabricWhereby the length of the rods are disposed the axial length of theresultant fabric wrapping, and the resin of the fabric enters theinterstices between adjacent rods, spirally wrapping a glass fiberfabric impregnated with a hardenable binder resin about said wrappedfabric and about said rods to form several superimposed layers upon saidrods so that the resin of said last mentioned fabric enters theinterstices between adjacent rods, and permitting said resin to hardento bond adjacent layers of fabric to each other and said layers offabric to said rods to provide an integral, homogeneous, bonded member.

2. In a method of forming an elongated construction member of glassfiber as in claim 1 wherein said fabric consists of glass fiberfilaments primarily disposed in the longitudinal direction of saidmember.

References Cited UNITED STATES PATENTS PHILIP DIER, Primary ExaminerU.S. Cl. X.R.

